Control system for movable roof supports and the like



Jan. 16, 1968 F. J. FUELL ETAL 3,363,515

CONTROL SYSTEM FOR MOVABLE ROOF SUPPORTS AND THE LIKE Filed Oct. 21, 1965 6 Sheets-Sheet 1 m@ 9 3 m mm 3 mm lNvEN-roizs FREBRIQK J. Fueu. JOHN L. FOWLER BY will), 6014.. M4

A'r-roangy Jan. 16, 1968 F.J. FUELL ETAL CONTROL SYSTEM FOR MOVABLE ROOF SUPPORTS AND THE LIKE Filed OCC. 21, 1965 e Sheets-She d 5 \mvewroas Fazomcn J. Fueu. JOHN L. Fowuaa wean, M, 93M warm ATTORNEY CONTROL SYSTEM FOR MOVABLE ROOF SUPPORTS AND THE LIKE Filed Oct. 21, 1965 6 Sheets- Sheet 4 INVENTORS FREDR\CI J FUELL JOH L.FowLER wan),

ATTORNEYS Jan. 16, 1968 F.J. FUELL ETAL 3,363,515

CONTROL SYSTEM FOR MOVABLE ROOF SUPPORTS AND THE LIKE Filed Oct. 21, 1965 6 Sheets-Sheet 5 lNveN'rORS FREDRICK J. FUELL JOHN L. FOWLER BY I Loo-13 ,Ca- -L. 01.14. n)

ATTORNEYS Jan. 16, 1968 F. J. FUELL ETAL 3,363,515

CONTROL SYSTEM FOR MOVABLE ROOF SUPPORTS AND THE LIKE 6 Sheets-Sheet 6 Filed Oct. 21, 1965 FIG] INVENToRs FREDQCK J. Fueu.

JOHN L. FOWLER BY LOGBM/CALL,

ATTORNEYS United States Patent 3,363,515 CONTROL SYSTEM FOR MOVABLE ROOF SUPPORTS AND THE LIKE,

Frederick J. Fuel] and John Lawrence Fowler, Heston,

England, assignors to Fairey Engineering Limited, Heston, England, a company of Great Britain Filed Oct. 21, 1965, Ser. No. 499,777 Claims priority, application Great Britain, Oct. 22, 1964, 43,190/ 64 10 Claims. (Cl. 91-217) ABSTRACT OF THE DISCLOSURE An automatic hydraulic control system for controlling sets of hydraulic roof supports comprising a series of roof support frames each incorporating two roof support rams, each frame being mechanically coupled to an adjacent frame by a hydraulic advance ram, and each frame incorporating a separate hydraulic-powered automatic sequence controller arranged to be actuated in response to a hydraulic control pressure to advance that frame one step relatively to the adjacent frame by means of the hydraulic rams, the sequence controllers of the successive frames of the series being connected in cascade to the source of the control pressure so that on completion of the operative advance sequence of each sequence controller the control pressure is automatically admitted to the sequence controller associated with the next succeeding device to initiate its operative sequence.

This invention relates to hydraulic control systems for automatically performing a cycle of operations. The invention is particularly, although not exclusively, applicable to systems for the automatic sequential control of sets of hydraulic roof support units for use in mining, although it may also have applications in connection with the sequential control of other hydraulic-powered devices such as machine tools.

In the so-called plough technique of mining developed for use with long-wall coal faces, two parallel tunnels called roadways are cut some 200 yards apart and a temporary tunnel is established between them. A ploughtype cutter carried on a flexible conveyor traverses the entire length of the temporary tunnel, shearing off coal at a linear rate of 7S feet/min. The roof of the temporary tunnel is supported by a row of hydraulically-powered roof support units spaced about feet apart from one another, and as the temporary tunnel advances laterally due to the removal of coal from the face, the support units have to be advanced correspondingly to support the roof above the conveyor. Each support unit normally comprises a pair of frames, each frame comprising a front and a rear hydraulic roof support ram whose casings are rigidly connected together by a yoke, and the frames being coupled together side-by-side with the support rams in a quadrilateral plan by a horizontal advance ram, by which one frame can be advanced with its two supports lowered while the other frame whose supports are raised against the roof acts as a fixed abutment against which the advance ram thrusts. The supports of the frame which has been advanced are then raised, the supports of the other frame are lowered, and the advance ram is actuated again to advance the latter frame whose supports are then raised again, thus completing the forward stepping cycle of the complete unit of two frames.

Hydraulic-powered walking roof support units have in general either been manually-controlled, in which case it is necessary for an operator to manipulate a number of control valves in succession in order to cause the successive support units of a set of perhaps 20 units to move 3,363,515 Patented Jan. 16, 1968 a step forwards or backwards in turn, or have involved a costly and complicated fully-automatic electro-hydraulic control system.

The present applicants copending U.S.A. patent application No. 442,551 describes a semiautomatic control system for a set of hydraulic roof supports (or other hydraulically-actuated devices) in which there is provided a pair of electro-hydraulic sequence controllers each programmed to initiate three or more operations in sequence certain of which are reversals of the others, and a reversing device for reversing one operation of each three, the two sequence controllers being actuated successively to cause either a complete forward stepping cycle or a complete backward stepping cycle of a support unit of two support frames coupled together by an advance ram. Each forward or reverse stepping cycle of each support unit has to be triggered off by manual operation of an individual control at a central control panel.

The present invention has for its object to provide a simple fully-automatic hydraulic control system suitable for initiating and controlling in sequence the forward steps of a set of hydraulic-powered support units, no automatically-controlled reverse stepping movement of the complete set being required. Another object is to eliminate the need for electrically-operated components in the control system and to provide a system actuated solely by hydraulic power.

According to the present invention, in an automatic control system for sequentially operating a series of hydraulic devices each incorporating two or more hydraulic motors requiring to be actuated in a predetermined se quence, each hydraulic device incorporates a hydraulic sequence controller actuated in response to a hydraulic control pressure and arranged when so actuated to initiate the actuation of the hydraulic motors of the associated device in the correct sequence, and the sequence controllers of the successive devices are connected in cascade to the source of control pressure, the connection being so arranged that the completion of the operative sequence of each sequence controller automatically admits the control pressure to the sequence controller associated with the next succeeding device to initiate its operative sequence.

Each of the said hydraulic devices may comprise one frame of a two-frame roof support unit whose advance ram is common to both frames, each frame having two roof support rams. Thus each frame will be provided with its own hydraulically-powered autoamtic sequence controller arranged when actuated first to lower the two roof support rams, preferably simultaneously to save time, then to operate the advance ram to advance that frame one step, and then to raise the two support rams once more preferably simultaneously. At the end of its operative sequence the automatic controller will operate hydraulic valve to admit the control pressure to the control of the adjacent frame thereby initiating the forward stepping sequence of that frame.

Thus the automatic control system when set into operation will cause a complete cycle of successive forward steps to be performed in turn by the frames of a set of support units, without any need for individual manual control of the stepping movement of each frame or of each unit of two coupled frames.

The sequence controller of each frame may comprise a hydraulic ram and at least one row of hydraulic servo valves spaced apart along the line of action of the ram plunger and arranged to be actuated in turn by the ram plunger during its axial stroke when the ram is energised by the control pressure, the hydraulic servo valves selecting the sequential operations of the roof support and advance rams.

For example there may be two parallel rows of hydraulic servo valves grouped in pairs, the two valves of each pair being positioned to be actuated simulaneously by the ram plunger and the pairs of valves being actuated successively as the ram plunger performs its axial stroke.

Preferably the hydraulic system from which the control pressure for operating the sequence controllers is derived is entirely separate from that used to actuate the roof support rams and advance rams, thus ensuring that there is no risk of a build-up in pressure occurring in one hydraulic ram or in the rams of one unit and interfering with the correct operation of the control system to cause malfunctioning of another unit.

Means is preferably also provided for opera-ting the rams of each frame manually if required, to enable each support unit to be controlled manually independently of the other units if required.

The invention may be carried into practice in various ways, but one specific embodiment will now be described by way of example only with reference to the accompanying drawings, in which FIGURE 1 is a diagram showing in plan a set of two-frame roof support units and their hydraulic interconnections,

FIGURE 2 is a diagram of the hydraulic circuit of one frame of one of the support units of FIGURE 1 and of its hydraulic sequence controller,

FIGURE 3 is a sectional elevation, on the line III III of FIGURE 4, of the sequence controller of one frame,

FIGURE 4 is a plan, partly in section on the line IVIV of FIGURE 3, of the sequence controller of FIGURE 3,

FIGURE 5 is a section on the line VV of FIGURE 4, and

FIGURES 6 and7 are sections on the lines VI-VI and VII-VII of FIGURE 3.

In the illustrated embodiment, the invention is applied to a set of n twin-frame roof support units 10A, 10B ION, as shown in FIGURE 1, of which each frame 11 or 12 comprises two simultaneously-operated vertical hydraulic roof support rams 13A, 13B and shares a horizontal advance ram 14 with the companion frame 12 or 11 of the unit. The units of the set are connected in cascade (as shown in FIGURE 2) to a hydraulic control pressure system 15 separate from the main hydraulic pressure system 16, 17 by which the roof supports and advance ram of each unit are actuated. Each frame 11 or 12 is provided with an associated automatic sequence controller 20 shown in detail in FIGURES 3 to 7, which comprises a hydraulic ram 21 Whose casing 22 is strapped to the yoke 23 of the frame, and whose plunger 24 actuates six normally-closed hydraulic poppet valves 25A, 25B, 26A, 26B and 27A, 27B in a desired sequence. At its end the valve plunger 24 carries a pivoted U-shaped link plate 28 (FIGURE 3) the ends of whose two arms are pivoted to the plunger 24 by means of a pin 29, and a pair of spaced coaxial roller cams are pivotally mounted on the yoke of the link plate 28 by means of a pin 31. The link plate 28 can rock about the pivotal axis of the pin 29 which is transverse to the axis of the ram plunger 24 to swing the roller earns 30 between a retracted position in line with the plunger 24 and clear of the poppet valves 25A to 27B, and an operative position shown in FIGURE 3 in which they project on one side of the plunger 24 to actuate the poppet valves 25A to 27B in pairs as the plunger 24 is advanced. The subsequent retraction of the plunger 24 swings the link plate 28 and the roller earns 30 back to their retracted positions so that the roller cams 30 will not actuate the poppet valves 25A to ME during the return movement of the plunger 24.

he poppet valves 25A to 273 of the sequence controller 20 are arranged in pairs in two rows extending side by side, the two poppet valves of each pair being mounted side by side on opposite sides of the ram plunger 24 and the three pairs being spaced apart in the direction of movement of the ram plunger. The two poppets of each pair are operated simultaneously by the two roller cams 30 as the plunger 24 advances, and close again simultaneously after the roller cams 30 have passed from them. Each poppet valve is provided with a rocking tappet 32 mounted on a transverse spindle 33 and having a ramp surface 34 to be engaged by the associated roller cam 30 as it passes, and an actuating surface 35 bearing on the end of the poppet valve rod 36 to open the poppet valve against a spring 37 normally tending to keep it closed. As shown in FIGURE 7 the rockers 32 associated with the poppet valves 26A and 26B are mounted on a common spindle 33. Moreover four of the poppet rocker spindles 33 (on which five of the rockers 32 are mounted) are provided with individual stub extensions 38 which extend through the valve casing as shown in FIGURE 7 and are provided with hexagonally-recessed heads 40 to be engaged by a key to allow the manual opening of the five poppet valves 25A, 25B, 26A, 26B and 27A. The four hexagonally recessed heads 40 are housed in chambers normally closed by a pivoted access door 41. The sixth poppet valve 27B, that controlling the servo pressure of the control system 15, is not provided with a stub extension 38 and head 40.

The first pair of opposed poppet valves 25A and 25B, i.e. that nearest to the sequence controller ram 21, are partially-balanced hydraulically and when opened simultaneously by the cams 30 of the plunger 24 they respectively connect the casings of the two support rams 13A and 13B of the associated frame 11, say, via lines 42, 43 to a low-pressure return line 17 leading to the reservoir of the main hydraulic system, as shown diagrammatically in FIGURE 2, thus causing the two support rams 13A, 1313 to lower themselves. The second pair of poppet valves 26A and 2613, which are also partially-balanced hydraulically, are connected respectively via lines 44, 45 to the opposite ends of the common advance ram 14 as sociated with the frame 11 and its companion frame 12 of the same unit, and when they are opened simultaneously by the further advance of the ram plunger 24 the valve 26A connects one end of the advance ram 14 to the hydraulic pressure line 16 of the main system whilst the other valve 26B connects the other end of the advance ram 14 to the return line 17, via line 43, thus actuating the advance ram 14 to move the frame 11 forwards one step. or the third pair of poppet valves, the valve 27A is a partially-balanced valve which when opened by the continued movement of the ram plunger 24 admits the hydraulic pressure from the main system line 16 via lines 47 and non-return valves 48 into the lines 42 and 43 leading to the two roof support rams 13A and 13B, to raise them again into a roof-supporting position after the forward stepping movement of the frame 11 has been terminated by the closure of the second pair of valves 26A and 2613. The other valve 27B is a non-balanced poppet valve which controls the servo or control pressure of the control system as will now be described.

The hydraulic sequence controller ram 21 is an unbalanced hydraulic ram to the smaller or annulus end of which (i.e. that having the smaller effective piston area) the hydraulic pressure of the main system is permanently connected by an extension 49 of the pressure line 16, and to the larger or full-bore end of which the control pressure can be admitted via line 50 connected to the control pressure line 15 leading from the preceding frame (or from the control pressure system direct via a manual valve in the case of the first frame of the series) and an adjustable needle valve 51. When the control pressure is supplied from line 15 to the larger end of the controller ram 21 it overcomes the thrust of the main system acting via line 49 on the other end of the controller ram 21 and starts to advance the ram plunger 24. The rate of advance of the ram plunger is controlled by the adjustable needle valve 51. The sixth poppet valve 27B when opened by the ram plunger 24 at the end of its stroke admits the control system pressure from the line to a line (15 in FIGURE 2) leading from the frame 11, say, to the sequence controller of the next adjacent frame, 12, thus triggering off the actuation of the sequence controller 20 of the latter frame to initiate the stepping sequence of that frame. However the application of the control pressure via the line 15 to the sequence controller 20 of the earlier frame 11 is not interrupted by the opening of the sixth valve 27B, so that the controller ram plunger 24 remains at the end of its forward stroke and does not start its return stroke under the force of the main system pressure so long as the control system pressure remains effective. It should also be noted that the ram plunger 24 when at the end of its forward stroke holds the third pair of poppet valves 27A and 278 open, thus permitting the continued admission of control system pressure to the larger end of the control ram 21 via the line 50 and restrictor 51, and of main system pressure to the front and rear support rams 13A and 138 via the lines 47, 42. Loss of pressure in the support rams 13A and 13B is guarded against by the nonreturn valves 48, which also prevent inter-action between support rams.

The operation of the control system will be apparent from the previous description. Thus when a manual control valve 60 (FIGURE 1) is opened at the central control panel (not shown) to admit the control pressure via line 15 to the larger end of the sequence controller ram 21 of the first frame 11 of the first two-frame support unit 10A in the set or row, this single manual operation will set the automatic control system into operation and the complete cycle of successive forward stepping movements of the successive support frames 11 and 12 of the units 10A to ltlN will be performed in turn until the whole group of units has moved forward, the completion of the stepping sequence of each frame automatically triggering off the sequence controller 20 of the next adjacent frame for forward movement. The controller rams 21 of the frames 11 and 12 will remain fully stroked (extended) until the last unit ION has completed its step forward at the end of the complete stepping cycle, when the closure of the manual control valve 60 will shut off the control pressure from all frames, and a second valve 61 will be opened to connect the control line 1545' to reservoir, enabling the controller rams 21 to retract in readiness for a further stepping cycle. A four-way manual selector valve might be provided in the control panel to incorporate the two valves 60 and 61 for controlling the initiation and completion of the whole stepping cycle.

It is possible to interrupt the stepping cycle at any point simply by closing the manual control valve 60 without connecting the control pressure line to reservoir via the other valve 61, but if this were done at an instant when one of the poppet valves of a frame was held in the open position manually by the head 40, this might prevent further functioning or cause malfunctioning of the sequencing procedure. To avoid risk of this happening, a further manually-operated valve 62 is incorporated in each frame sequence controller circuit, being a rotary valve which is coupled to the hinged door 41 which covers the hexagonally-recessed heads 40 of the rocker spindles 33. When the door 41 is opened, its opening movement automatically opens the rotary valve 62 to connect the larger end of the control ram 21 via a line 63 to the low-pressure return line 17 of the main system and bypasses the control pressure via a line 64 to the line 15 leading to the next frame. Thus to safeguard the control ram 21 against inadvertent manual operation during an interrupted and incomplete automatic cycle, the rotary valve 62 ensures that before access to the manual facility through the opened door 41 is obtainable the frame in question will be completely bypassed and isolated from the automatic control system pressure 16, and its controller 20 will be reset automatically in readiness for manual operation. Thus an operator may interrupt a group stepping cycle, isolate a faulty unit, complete the stepping cycle of the remaining units, and deal with the faulty unit manually at leasure.

To guard against pressure build-up in the roof support rams 13A and 13B of any frame under load conditions, a yield capsule 65 is connected to each of the pressure lines 42 leading to the two support rams of that frame. When opened by an excess pressure in the line 42, the yield capsule relieves the pressure to the return line 17.

It is considered that with the use of the fully-automatic hydraulic control system described and illustrated, a single operator will be able to control adequately two sets of twenty support units from a central location, the two sets of units being located one on either side of the control location. This should enable an entire face to be controlled by only three operators, using cascaded sets of twenty units each, although sub-division of the set groups may be employed if desired under certain circumstances. An average advancement time of 7 seconds per frame is expected to be feasible.

If it is desired to preserve a right-to-left (or left-toright) sequence of forwarding stepping in each set of support units, with control from a central location between two sets, the hydraulic pipework 15, 15', 16 and 17 interconnecting the adjacent frames 11 and 12 and the adjacent units 10A, 10B etc. may be duplicated and provided with appropriate non-return valves to allow for operation and control from either end without change of sequence direction.

The system as described above does not provide for the control of the conveyor advance rams of the installation. As these must be pressurised sequentially to advance the conveyor, using the raised support units 13A, 13B as abutments against which to thrust, the control of the support unit stepping cycle and of the conveyor advance ram cycle may be integrated if desired.

What we claim as our invention and desire to secure by Letters Patent is:

1. An automatic hydraulic roof support system which comprises a series of roof support frames each incorporating two hydraulic roof support rams, each frame being mechanically coupled to an adjacent frame by a hydraulic advance ram, and each frame incorporating a separate hydraulic-powered automatic sequence controller, supply conduit means for supplying hydraulic fluid under pressure to said rams, return conduit means for conducting said fluid from said rams, and means for actuating the sequence controller of the first frame of said series to first connect said support rams of said first frame to said return conduit means to lower said support rams, then to connect the respective ends of said advance ram to said supply and return means, respectively, to cause said advance ram to advance said first frame relative to said adjacent frame, then to connect said support rams of said first frame to said supply means to raise said support rams, and then to actuate the sequence controller of the adjacent frame to perform a like series of operations.

2. An automatic roof support system as claimed in claim l-including a main hydraulic pressure system connected to the roof support rams and advance rams of the frames to actuate the said rams under the control of the sequence controllers, and a hydraulic control pressure system, separate from the main system, to which the sequence controllers are connected in cascade to be energised in sequence thereby.

3. An automatic roof support system as claimed in claim 2 in which each roof support frame comprises a front vertical roof support ram and a rear vertical roof support ram coupled together mechanically by a yoke, and in which the roof support frames are slidably joined together in pairs, each pair of frames sharing a common advance ram which controls their relative sliding movement, and each pair of frames constituting a separate roof support unit.

4. An automatic roof support system as claimed in claim 3, said support rams of each said frame being simultaneously connected to said return conduit means and then to said supply conduit means.

5. An automatic roof support system as claimed in claim 1 in which the sequence controller of each frame comprises a hydraulic ram and at least one row of hydraulic servo valves spaced apart along the line of action of the ram plunger and arranged to be actuated in turn by the ram plunger during its axial stroke when the ram is energised by the control pressure, the hydraulic servo valves selecting the sequential operations of the roof support rams and advanced ram.

6. An automatic roof support system as claimed in claim 5 in which each sequence controller includes two parallel rows of servo valves grouped in pairs, the two valves of each pair being positioned to be actuated simultaneously by the ram plunger and the pairs of valves being actuated successively as the ram plunger performs its stroke.

7. An automatic root support system as claimed in claim 6 in which means is provided for operating the rams of each frame manually independently of one another and of the other frames.

8. An automatic roof support system as claimed in claim 7 in which the said manual operating means comprises means for manually opening and closing the servo valves of a sequence controller independently of one another.

9. An automatic roof support system as claimed in claim 8 in which each sequence controller incorporates automatic hydraulic bypass valve means arranged when operated to isolate the sequence controller from the control pressure system and to connect the control pressure system through to the sequence controller of the next frame, bypassing the isolated controller, and a safety interlock aranged to automatically operate the bypass valve before the manual control means is rendered accessible.

10. An automatic roof support system as claimed in claim 9 in which the manual control means is enclosed by a hinged door, and in which the bypass valve is coupled to the hinge of the door so as to be operated automatically by the opening of the door.

References Cited UNITED STATES PATENTS 3,217,603 11/1963 Potts et al. 9ll89 3,264,945 8/1966 Bolton et al. 9ll89 FOREIGN PATENTS 1,201,174 7/1959 France.

MARTIN P. SCHWADRON, Primary Examiner.

PAUL E. MASLOUSKY, Examiner. 

